This invention relates to a dual wall combustor for a gas turbine engine. More particularly, this invention relates to a dual wall combustor including a ceramic matrix composite shell that supports a liner assembly.
A combustor for a gas turbine engine includes an outer shell and an inner liner. The inner liner is directly exposed to combustion gases and defines a gas flow path. The inner liner is spaced apart from the outer shell to define an air-cooling passage for cooling and controlling the temperature of the inner liner. Both the inner liner and the outer shell are fabricated from a material capable of withstanding the extreme temperatures generated during the combustion process.
During operation, the inner liner is exposed to thermal gradients caused by the flow and swirl of the fuel air mixture as it is ignited to generate combustion gases. Such differences in temperature cause the thermal gradients within the inner liner. A design concern is providing an inner liner material and configuration that accommodates such gradients. As appreciated, not all materials that perform favorably at high temperatures can also withstand the thermal gradients and the strains produced by such differences in temperature. Disadvantageously, the stress and strains generated in the inner liner by the thermal gradients have complicated the use of many materials capable of withstanding the elevated temperatures produced during combustion.
One example material includes ceramic matrix composites. A ceramic matrix composite includes ceramic fibers interwoven into a sheet that is than impregnated with a material such as Silicon Carbide, Silicon-Nitride or other oxide components that are capable of withstanding elevated temperatures. As appreciated, higher temperatures within a combustor are favorable to provide a more efficient burning of fuel. However, the ceramic matrix composite does not respond favorably to thermal gradients and therefore has not been widely utilized in conventional combustors.
Accordingly, it is desirable to develop a combustor that utilizes the advantageous thermal properties of ceramic matrix materials within a combustor without compromising combustor strength and durability.